Automatic station



* 1, 1 March 1927' c. A. BUTCHER 6 9459 AUTOMATIC STATION Filed May as,'1923 2 Sheets-Sheet 1 WITNESSES: 10 N INVENTOR "Y I Char/es A.fiufckeir ATTORNEY c.A. BUTCHER- AUTOMATIC STATION 4 March 1, 1927.

Patented Mar. 1, 1927.

UNITED STA ES Parent emu-1.

CHARLES A. BtJlIICHEIl-t OF EAST PITTSBURGH, PENNSYLVANIA, ASSIGNOR TOWEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN-'snvmm.

Application filed may 28,

My invention relates to automatic stations and particularly toprotective and control systems for controlling translating apparatussuch asmot'or. generator units in such stations.

One object of my invention is to provide a protective system for asynchronous motorgenerator set whereby non-synchronous operation of themotor may be detected to protectthe motor'irom overheating by reasonthereof.

Another object of my invention is to pro-' I vide means whereby theexcitation of the generator may be quickly controlled to limit thevoltage thereof, depending upon the operating conditionof the motor.

Another object of my invention is to provide a system whereby theexcitation of the generator maybe controlled according to apredetermined condition of the load circuit to preclude a" tendency forthe current to reverse through the generator.

Another object of my invention is to provide a control system wherebythe load upon the generator may normally be maintained below apredetermined maximum value but a relatively. larger value of currentpermitted to traverse the generator, when it 'first assumes a portion ofthe load, While the temperature of the windings of the machine is lessthan the predetermined value.

These and other objects will, appear more fully from a consideration ofthe system described in connection with the accompanying drawings.

In practicing my invention, I provide a current transformer in circuitwith the field winding of the synchronous motor to energize a relay whenthe motor is pulled out of synchonism by reason of an excessive loadthereon. During normal operation, the relay will, of course, not beenergized. In or-,

- der to quickly peduce the load upon the generator topermit the motorto return to synchronous operation, *I dispose a resistor in circuitwith the field winding of the generator-to reduce the voltage .thereof..Normally,

; the resistor is short-oi'rcuited. Upon the ditions, such asthe motorbeing pulled o'ut @firrenceoipredetermined abnormal con- 1923. SerialNo. 641,868.

short-circuiting means is rendered ineffective and the resistor becomeseffective to limit the excitation of the generator field windmg.

In order to protect the generator from overheating, I provide a thermalrelay that reproduces the thermal conditions in the generator windings.A regulator is also provided to control the voltage of the generatorto'preclude more than a predetermined value of current from beingsupplied thereby to a load circuit. However, inasmuch as the temperature of the generator, when first connected to the system, isrelatively low and it is capable of a sustained overload for theingenerator current below the predetermined maximum value.

In automatic substations containing apparatus that may be connectedautomaticall to a system upon a demand for energy, or disconnected whensuch demand ceases, protective'devices of different kinds, that areresponsive to different conditions, are provided to protect theapparatus from such abnormal conditions. Some of such protective devicesare arranged ;merely to disconnect the apparatus from the systemtemporarily, andto permit a subsequent automatic reconnection. Otherprotective devices, however, are'arranged to lock out the apparatus topreclude further automatic connection to the system until the faultycondition has been cleared or eliminated and the protective de-' vicesmanually reset by an attendant.

In view of the number of such devices thatmay be employed to lock outthe apv paratus to preclude further automatic conthe apparatus, when thestation-is subsequently inspected. I therefore providean vices.

annunciator relay which is operated ly any one of the predeterminedlockout protective devices to preclude further automatic operation ofthe station and, at the same time, to indicate which of the protectivedevices effected its operation.

Figure 1 of the accompanying drawing is a diagrammatic view of anelectrical system containing apparatus arranged to operate in accordancewith my invention, and

Fig. 2 is a schematic diagramillustrating, in simplified form andarrangement, the respective circuits of'the various operating de-Referring to Fig. 1 of the accompanying drawings, alternating-currentenergy is derived from a source 1 of alternating-electromotive force andtranslated to direct-current energy, by means of a synchronous motor 2and a direct-current generator 3, which is then supplied to adirect-current circuit 4. The synchronous motor 2 is provided with afield winding 5 and the generator 3 is pro: vided with a field winding6. Energy for these windings is supplied by an exciter generator 7. a

A plurality of auto-transformers 8, that are energized from the circuit1 through a switch 9, are employed to provide a relatively smallstarting potential for the motor 2, which is applied thereto through astarting switch 10. After the motor is accelerated to synchronous speed,the switches 9 and 10 are opened to remove the starting voltage from themotor 2, and a running switch 11 is closed-to impress normal operatingvoltage upon the motor.

The initiation of the operation of the system is efi'ected by means of avoltage relay 12 which is responsive to the voltage of thedirect-current circuit 4: and serves to indicate a demand for energythereon. Control energy for operating the various control devices,before the amt is accelerated to suiticient speed to provide energy fromthe exciter, is procured from the circuit 1 through a transformer 13 andis supplied through a manually-operated switch 14 to two controlconductors 1g and 16. 1

When the relay 12 closes, by reason of low voltage on the circuit 4, acircuit is c0m pleted to energize a relay switclr17, as illustrated incircuit B in Fig. 2, from the control conductor 15 through the resistorand operating coil of the relay switch 17, the relay switch 12, amanually-operable switch 18 in its lower osition, an interlock switch 19of the trans ormer switch 9 and an interlock switch 20 of the runningswitch 11 to the other control conductor 16. The switch 17 is thereuponclosed. y Switch 17, in .closing,.completes the circuit of the operatingco l of a, master relay switch 21. This circuit may be traced, asillustrated in circuit C of Fig. 2, from control conductor 16 throughswitch 17 operating coil of relay 21, a resistor 21, an over-. speedswitch 22, a switch 23 of an annunciator and lock-out relay 24 to theother control'conductor 15. ,The relay 21 is thereupon energized toclose its two switches 25 and 26.

The switch 25, upon closing, connects the operating coil of a relayswitch 27 between the control conductors 15 and 16, as illus trated incircuit E in Fig. 2. The relay 27 thereupon closes its two switches 28and 29.

Switch 28 is connected in parallel with the rela switch 17 and serves tomaintain a hol ing circuit thereafter for the relay 21, irrespective offluctuations in the operation of the relay 12, which might otherwise,consequently, cause fluctuations in the operation H of relay 17. Theswitch 29, when closed, connects the control conductor 15 to anauxiliary control conductor 15A.

The various protective devices associated with the station are disposedto render the relay 21 and, consequently, the relay 27 inefi'ective,thereby effecting the deenergization of the auxiliary control conductor15A to permit the various control devices energized therefrom to beimmediately deenergized.

Immediately after the energization of the auxiliary control conductor15-..A, a relay switch 30 is energized between the conductor 15-A andthe conductor 16, as illustrated in circuit F shown in Fig. 2. The relayswitch 30, upon being energized, closes its switches 31 and 32.Simultaneously with the energization of the auxiliary control bus.conductor 15A, a second auxiliary control bus conductor 15'B isenergized from the conductor 15-A' through back interlock switch 33 ofone of the main direct-current switches 34' for connecting the generatorto the direct-current circuit 4.

and 39. Theswitch 39, while closed, serves to preclude prematureconnection of the generator to the direct current circuit, in a mannertobe hereinafter described.

The switch 38, upon closin completes the energizing circuit of a re ayswitch 40,-

through the back interlock switch of a holding; relay 41, between thecontrol conductors 15B and 16, as is illustrated in circuit H.

,The closing coil of the starting switch 10 is thereupon connectedbetween the control conductors 15.and 16, as illustrated in circuit I,to close the starting'switch 10' The switch 10, while closin its maincontacts, closes three front inter ock switches 43, 44 and i and opens'aback interlock switch 46.

The interlock switch 45, when closed, cooperates with the switch 38 ofthe relay switch 35, as is illustrated in circuits H and J, to connectthe operating coil of the hold.- ing relay 41 between the controlconductors 15B and 16. The starting switch is thereupon held in closedposition by the holding relay 41 and the closing coil is deenergizedupon the consequent deenergiza? tion of the closing-coil relay b theback interlock switch of the holding re ay 41.

The interlock switch 43 of the starting switch 10, u on being closed,cooperates with the inter ock switch of the holding re- I lay 48associated with the transformer energizin' switch 9 to connect a relay49, associate with the closin coil of switch 9, be-

. tween the control con uctors 1'5B and 16,

as is illustrated in circuit Kin Fig. 2. The

. relay 49 thereupon connects the closing coil closing coil of theswitch 9 is thereupon de-' energized.

Reduced starting electromotive force is now impressed on the motor 2which is gradually accelerated to synchronous speed. The transfer fromrelatively small startin voltage to normal operating voltage is e fectedwhen the starting current decreases to a predetermined minimum value andwhen the field winding of the motor subsequently becomes ener ized to apredetermined degree, thus 0 ecking, by different electrical conditions,the attaining of synchronous speed. The condition of minimum startingcurrent is indicated by a current relay 55- which is ener ized by acurrent transformer 56 in accorifii'nce with the starting current. Theenergization of the field winding of the motor is indicated by a relay57 that is connected in series therewith and that operates, whenenergized to a predeterm'ned degree, to open a back interlock switc 58and to close a front interlock switch 59. I

When both the starting current relay 55 and the field current'relay 57are energized to predetermined degrees, the current relay switch 55 willcooperate with the switch 59 of the field relay connect the operatingaeiaeee coil of the transfer relay 37 between the conductors 15A and 16,as illustrated in circuit N. The transfer relay 37 is thereupon operatedto open its back interlock switches 36 and 53 and to close two-frontinterlock switches 60 and 61. s

Switch 60,- when closed, serves to maintain a holding circuit for therelay 37 by connecting the coil between the conductors iii-A and 16, asillustrated in circuit N.

Immediately upon the operation of the transfer relay 37, the backinterlock switch l 36 opens to deenergize the operating coil of therelay 35 (circuit G). Interlock switches 38 and 39 of the latter relayare thereupon opened. Switch 38, in opening, deenergizes the holdingrelay 41 of the starting switch 10 which permitsthe latter to open(circuits H and J). Simultaneously, the opening of the interlock switch.53 by the transfer relay 3'? deenergizes the holding relay 48 (circuitM) associated with the transformer energizingswitchll. Theauto-transformers 8 are thereupon disconnected from the circuit and thestarting voltage removed from the motor 2.

Immediately upon the opening of starting switch 10 and the subsequentclosing of its interlock switch 46, the circuit of the closin coil relay62 associated with the running switch i1 is energized, as is illustratedin circuit =P, from the control conductor 16, throu h the frontinterlock switch 61 of the transrer relay 3?, the back interlock switch46 of the starting switch 10, the operating coil of the relay 62, theinterlock switch of a holding relay 63 and the hack interlock switch 50of the transformer-char izing switch 9 to the other control con uctorl5-A.

The relay 62 thereupon ener izes the closing coil of the running switcthe latter (circuit Q), whereupon the back interlock switch 20 and twoother back interlock switches 64 and 65 are opened and.

till

ll to close three front interlock switches 66, 67' and 68 are closed.Switch 66 completes the energizing circuit of the holding relay 63, asshown in circuit R, to hold the switch 11 closed. Full operating voltageis now applied to the synchronous motor 2 and it continues to operateuntil otherwisecontrolled by the protective devices, as will be herein-'after explained.

The back interlock switch 20 of the running switch 11 and the backinterlock switch 19 of the transformer-energizing switch 9 serve, whenopen, to disconnect the relay 17 from the energizing control circuit,since that relay is no longerneeded (circuit B').

nous speed and the exciter voltage gradually increases, energizing themotor and the generator field windin s. .Since the voltage of the directcurrent. circuit 4 to' which the. gen- 1:;- The motor is now operatingat synchro: if

erator is to be connected may vary considerably from the normaloperating voltage, it is desired to regulate the voltage of thegenerator until it corresponds to the voltage of the direct-currentcircuit before the generator is connected thereto.

For this purpose, a voltage regulator 70 is provided comprising twodifferentially operating and balancing coils 71 and 72, a balancedmember controlled thereby and a movable contact member 73 controlled bythe balanced member to engage either of contact members 74; and 75,depending upon the relative excitation of the coils 71 and 72. The coil71 is energized from the direct-current circuit 4 and the coil 72 isenergized from the direct-current generator 3. The

movable contact member'73will therefore be disengaged from the contactmembers 74- and 75 only when the voltage of the generator is equal tothe voltage of the direct-current circuit 4.

The voltage of the generator is regulated by means of a motor-operatedrheostat 76 that is connected in circuit with the field winding 6 of thegenerator across the terminals of the exciter 7. The rheostat 76 iscontrolled by a reversible mot or 77 (circuit MM), the filled winding ofwhich is-normally energized in one direction from the exciter 7 and thearmature of which is controlled by two switching devices 78 and 79 thatare operative, respectively, to effect the raising and the lowering ofthe generator voltage.

The voltage-raising switch 78 comprises an operating coil 80, threefront interlock switches 81, 82 and 83, that are closed when i theswitch is operated, and a back interlock switch 84 that is opened by theoperation of the switch. The voltage-loweringswitch 79 similarlycomprises an operating coil 85, front interlock switches 86, 87 and 88that normally are open and are closed by the operation of the switch 79,and a back interlock switch 89 that isnormally closed but is open whenthe switch 79 operates. The switches 78 and 79 also comprise holdingcoils 90 that are constantly energized and serve tomaintain the relays78 and 79 positively in their respective open positions when theoperating coils are deenergized.

While the generator voltage gradually increases,-the excitation of theline-excited coil 71 may exceed-that of the generator-excited coil72vand the contact members 73 ,and 74 willengage. Under such conditions,a circuit is completed to energize the operating coil of the voltae-raisin'g switch 78 This circuit may be traced from the'mid-point of aresistor 91 (circuit GG), that is energized from the exciter terminals,through (circuit HH) a back interlock switch 92, that is 7 closed in theopen position ofthe direct-current circuit breaker 34, through thecontact members 7 3 and 7t of the regulator 76 and the operating coil ofthe voltage-raising switch 78 to the negative terminal of the exciter.The voltage-raising switch 78 is thereupon energized to close itsinterlock switches 81, 82 and 83. i

The switch 81, in closing, permits current to traverse the armature ofthe rheostat motor 77 in such direction as to remove the effectiverheostat resistance from the circuit of the shunt field winding of thegenerator. This circuit may be traced from the negative terminal of theexciter through the limit switch 93 associated with the rheostat, theinterlock switch 81 of the raising switch 78, the armature of the motor77 and the interlock switch 89 of the voltage-lowering switch 79 to thepositive terminal of the exciter.

While the generator voltage is gradually increasing, the switch 83completes the energizing circuit for the upper anti-hunting coil 94which tends to cooperate with the coil 71 in such manner as to establishan artificial balancing efiect slightly before the generator voltageactually attains the value of the voltage of the direct-current circuit.

If the generator voltage should increase beyond the value of the voltageof the directcurrent circuit, the contact member 73 of the regulatorwould disengagethe contact member 74 and would engage the contact member75. The voltage-raising switch 78 would thereupon be permitted to returnto its initial position and the voltage-lowering switch 79 would becomeenergized (circuit J J to close its interlock switches 86, 87 and 88.Switch 86 would then complete the circuit of the armature of therheostat motor in a reversed direction, to insert resistance in thecircuit of the generator field winding, this circuit being traced fromnegative exciter through limit switch 93, interlock switch 86 oflowering switch 79, the armature of rheostat motor 77, and interlockswitch 84 of the voltgaged from both contact members 74 and 7 5' and theraising and lowering switches 78 and 79 will be in their respectivedeenergized positions. Under such conditions, the generator will then beconnected to the direct-current circuit in the following manner.

When the voltage of the exciter was developed, a polarity relay 96, asillustrated in circuit T, closed its switch to energize a volta e relay97 from the exciter. The relay 9%, as illustrated in circiiit U, closed,when energized to a predetermined degree, to connect the operating coilof a relay 98 between the conductors l5- -B and 16, as is illustrated bythe middle portion of circuit S,

The operating coil of relay 98 remained deenergized, however, while theraising and lowering switches 78 and 79 were being operated to regulatethe generator voltage,

by reason of the interlock switches 82 and 87 short-circuiting theoperating coil of relay 98, asmay-be seen by referring to the right-handportion of circuit S.

Moreover, the relay 98 was precluded from operating even after theexciter had developed a predetermined voltage, so long-as the volt-ageto be applied to the motor had not been transferred from starting torunning value, by reason of the switch 39 of the relay'35 being inclosed position to shortcircuit the operating coil of the relay 98. Therelay is otherwise employed to control th starting switch 10.

Still another switch, namely, the interlock switch 58 of the motor fieldrelay 57, short circuited the operating coil of the relay 98 to precludeits energization until the motor field was sufliciently energized *to'permit the motor to assume the normal operating load that would beplaced upon it in operating the generator. 1

Theseprecautions, in precluding the excitation and operation of therelay 98, are taken to prevent the connection of the generator to thedirect-current circuit until various'conditions in the motor and in thegenerator are attained, indicating normal operating conditions.

After the proper energizationof the motor field winding and thesubsequent transfer from startingto running voltage, and the developmentof proper electro-motive force by the generator, therelay 98 ispermitted to be energized and to close its switch.

The switch of the relay 98 cooperates with the interlock switch. 67 ofthe running switch 11, as is illustrated in circuit V, and the switch 26of the master relay 21 to connect the operating coil of a relay switch99 between the terminals of the exciter. The relay 99 is thereuponenergized to close two front interlock switches 100 and 101 and open aback interlock switch 102.

The interlock switch 102 is merely effective to insert a limitingresistor in circuit with the operating coil 99 to limit the currenttraversing the operating coil to a value which is sufiicient to hold therelay in closed position, but not suflicient to operate it. The switch100, when closed, parallels the relay switch 98 to maintain a holdingcircuit for the relay 99.

The switch 101, in closing, connects the closing coils of thedirect-current circuit interrupters 34 and 103 to the terminals of theexciter to energize the former, and the interrupters are thereuponclosed to connect another interlock switch 104, and closes two frontinterlock switches 106 and'107. The i switch 104 serves merely to inserta cur rent-limiting resistor in circuit with the closing coil to limitthe current that may traverse the same to a value that is suiiicient to'hold the interrupter closed.

The switch 33, in opening, disconnects the second auxiliary control bus15B from the first control bus 15-A, whereupon the moved from themovable contact member 73 of the voltage regulator 7 0 and the latter isrendered ineffective so long as the generator is connected to thedirect-current circuit.

The closing of the switch '107, howevfer,

impresses voltage upon a movable contact member 110 of a currentregulator 11-1.

The current regulator 111 thus becomes operative to control the voltageof the generator only after the generator has been connected' to thedirect-current circuit 4 and controls the generator voltage to precludemore than a predetermined value of current from being supplied to thecircuit by the generator during normal operation. 7 The normal operatingcoil 112 of the regulator 111 is energized from a portion of thegenerator winding that serves as a shuntto energize said coil inaccordance with the current traversing the generator.- The regu-' latoris adjusted to prevent the generator current from exceeding apredetermined value, by decreasing the voltage of the exciter field whenthe load upon the generator increases and tends to draw more currentfrom the generator.

Since the reason for limiting the current to a predetermined maximumvalue is to avoid overheating of the generator wind- I ings, it will berealized that, when the gen erator commences operation, more than suchmaximum value of current may be permitted to traverse the generatorwindings until the dangerous temperature is attained.

In order to permit the generator to assume more than its share of load,while the temperature of the generator windings is considerably belowthe dangerous temperature, 1 provide an auxiliary winding 113 whichserves to so modify the controlling eiiect of the current regulator 111as to establish an artificial condition indicating a current of lesservalue to be traversing the generator. When the temperature of thegenerator attains a predetermined value beyond which it is desired toavoid overheating the machine, a thermal relay 114 becomes operative todeenergize the modifying winding 113 (circuit BB), which had beenheretofore energized from the exciter. The relay 114 ries winding of thegenerator, it will oper-' ate in response to the potential drop acrossthat winding, which will be a function of the temperature thereof.

During the regulation of the generator 3 while its voltage is permittedto increase, a

- resistor 115, that is disposed in the circuit of the load thereon.

the shunt field winding 6 of the generator, I

is short-circuited by a switch 116 of a relay switch 117. The operatingcoil of the relay switch 117 is maintained energized by an interlockswitch 118 of a relay 119 (circuit Y), when the exciter voltage attainsa predetermined value.

The relay device 117 comprises, in addition to the interlock switch 116,a front interlock switch 120, that is normally open, and three backinterlock switches 121, 122 and 14.6. The relay 119 comprises, inaddition to the switch 118, a front interlock switch 123 and a backinterlock switch 124.

During normal operation, the relay 117 is energized to short-circuit theresistor 115 to permit the current regulator 111 to control. the voltageof the generator depending upon Upon the occurrence of abnormalconditions, such as the motor pulling out of synchronism by reason ofheated hearings or other overloading conditions, it is desired todeenergize the relay 117 to permit the resistor 115 to become efi'ectiveto reduce the excitation of the generator quickly.

In order to detect non-synchronousoperation of the motor, I dispose acurrent transformer 125 in the circuit of the motor field winding andprovide a relay switch 126 to be energized from the current transformer.The relay switch 126, when energized, opens a back interlock switch 127and closes a front interlock switch 128 which cooperates -with theswitch 123 of the relay 119 to shunt the coil of the relay 119 and,consequently, effect the deenergization of the resistor-controllingrelay 117.

An additional relay 129, that is responsive to the current thattraverses the generator, is provided to cooperate with the slipdetecting relay 126 in controlling the resistor-controlling relay 117.The relay 129 is arwill be in its open position.

ranged to close its contacts when the currenl traversing the generatordecreases to or be low the value corresponding to about onefourth offull load value.

Upon referring to circuit Z, the energizing circuit for the operatingcoil of the relay 119 may be more readily traced and the operation ofthat relay more easily comprehended. When the exciter voltage attains apredetermined value, the relay 119 is energized by a circuit proceedingfrom the positive terminal of the exciter through a resistor 130, theoperating coil of the relay 119, its interlock switch 121 and a limitingresistor 131 in parallel, thence through either of two paths, one ofwhich includes the back interlock switch 127 of the relay 126 and theback interlock switch 121 of the relay 117 to the negative terminal ofthe excitcr; the other path comprising the switch of the generatorcurrent-responsive relay 129 and a connection to the negative terminalof the exciter.

Therefore, .as soon as the exciter voltage attains a value that issufficient to energize the relay 119 to effect the operation thereof, itis actuated to its energized position, thereupon energizing the relay117 to short-circuit the resistor in the generator field circuit. In theenergized position of the relay 119, its front interlock switch 123 isclosed to maintain its own holding circuit.

If, now, some condition arises which pulls the motor out of synchronism,the relay 126 will become energized, and, after an interval dependingupon its time setting, will close its front interlock switch 128. Aswill be seen by referring to circuit Z, the switch 128, when closed,short-circuits the operating. coil of the relay 119, therebydeenergizing it and permitting it to return to its initial position. Therelay 117 is also thereupon .de-

energized and the resistor 115 is rendered effective to reduce theexcitation of the field winding of the generator.

Since the current supplied by the generator to the circuit 41 hasundoubtedly exceed ed the operating value of the current relay 129,which is adjusted to approximately onefourth of the generator capacity,its switch As the current traversing the generator gradually decreasesto a value corresponding to the setting of the current relay 129byreason .of the diminished field excitation, the relay switch 1.29closes. The short-circuit across the op erating coil of the relay 119will be maintained by the interlock switch 128 of the slip relay 126 solong as the motor is operating non-synchronously.

However, as soon as the resistor 115 becomes etfective to limit theexcitation of the field winding, and the load eventually decreases to avalue which permits the current relay switch 129 to close, the, motor isable to reassume the load'and again attain synchronous speed, Under suchconditions, the front interlock switch 128 of the slip relay 126 isopened and,.after a time interval, the switch 127 of the relay isclosed.

If the load upon the-generator has de creased to such value as wouldpermit closing of the current relay switch 129, the relay 119 will beenergized as soon as the front in terlock switch 128 of the slip relay126 opens. If the motor should reattain synchronous speed, however, at avalue exceeding the load value at which the current relay is adjusted toclose, the relay 119 would become energized after a relatively shortinterval required for .the back interlock switch 127 of the slip relayto reclose. The resistor-controlling relay 117 would thereupon beimmediately reenergized and the resistor 115 short-circuited to permitthe gradual assumption of the load by the generator.

In order to maintain the voltage of the generator substantiallycons'tantduring normal operation, while the'load thereon is less than thepredetermined maximum value, a third regulator 133 is provided tocontrol the excitation of the generator in the same manner as the otherregulators 70 and 111 are arranged to control the excitation thereof,namely, by means of the rheostat 76 and the voltage-raising andvoltage-lowering switches 78 and 79. The regulator 133 comprises anoperating coil 134:, a movable contact member 135, and two stationarycontact members 136' and 137 that are respectively adapted to be engagedby the contact memher 135, depending upon the relative degreeoflenergi'zation of the operating coil 134 relative to the adjustment ofa tension spring 138.

The regulators 111 and 133 are also provided with anti-hunting coils 94similar to those mentioned in connection with the regulator 70. Theoperation of this device is set forth in a copending application of RoyJ. Wensley, for voltage regulator systems,

filed August 28, 1922, Serial No. 584,613,.

and assigned to the Westinghouse Electric & Manufacturing Company.

The current load regulatorlll, which cooperates with the regulator 133to maintain the current below. a predetermined maximum value while thetemperature of thegenerator exceeds a predetermined value, is providedwith two contact members 139 and MO which are adapted to be respectively{engaged by the movable contact member 110, depending upon theefi'ective torque of the two windings 112 and 113, and of the wind ing112 when it alone is energized, relative to the tension of aspring 141.

As may be seen by referring to circuits GG and HH, only the voltageregulator is effective before the generator is connected to thedirect-current circuit to regulate the voltage of the enerator tocorrespond to that of the circuit, by reason of the interlock switch 92being closed and the switch 107 latter the generator is connected to thecircuit, the control voltage that is derived from the resistor 91, thatis connected be tween the exciter terminals, is transferred by theinterlock switch 107 of the direct-current interrupter 34 totheregulators 111 and 1333. Their operation then depends upon the load onthe generator and upon the operation of the resistor-controlling relay117.

During normal operation, when the resister-controlling relay 117 isenergized, the switch 122 of the relay .117 is open. Assuming that theoperating temperature of the generator has been attained and that themodifying coil 113 has been open-circuited,

' the regulator 111 will operate, to control the voltage of thegenerator, depending upon the load thereon.

Normally, the load will be less than the. maximum value for which thecurrent regulator 111 is adjusted. The contact member will thereforeengage ,the contact member 139 and impress control potential upon themovablecontact member 135 of the voltage regulator 133, from theresistor91 through the interlock switch 107 of the interrupter 34, the contactmembersllO and 139 of the current regulator 111 and the interlock switch120 of the resistor-controlling relay 117. The voltage regulator 133,under such conditions, will be effective to control the excitation ofthe generator field winding by cont-rolling the voltage-raising and thevoltage-lowering switching devices 78 and 79 to operate the rheostat 76.Thus, so long as the current does not exceed the maximum value, thevoltage regulator 133 controls the 1 generator voltage.

If the current should tend toexceed the normal operating load for whichthe current regulator 111 is adjusted, the contact memher 110 willdisengage the Contact member 139 and engage the contact member 140.Control potential will thereupon be removed from the movablecontactmember 135 of the voltage regulator 133 and the current regulator111 will operate directly to effect the lowering of the generatorvoltage by energizing the operating 'coil of the voltagelowering switch79 until the current decreases to the predetermined operating value andwill thereafter maintain the current at that value.

As will be seen upon referring to circuit LL, the excitation of thegenerator is con-- Inn trolled independently of the regulators upon theoccurrence of such abnormal conditions as eilect the deenergization ofthe resistor controllin relay 117. As soon as that relay is deenergized,its backinterlock switch 122 closes to immediately energize thevoltagelowering relay 79 to insert'the'resistance of the rheostat 76 incircuit with the generator field winding. As soon as the motorr'e-attains synchronous speed to re;assume the load, theresistor-controlling relay 117 is again energized, as explained above,and the interlock switch 122 opens to permit the regulators to becomeagain effective in controlling the excitation of the generator.

in addition to the slip responsive relay for controlling the excitationof the generator by controlling the resistor-controlling relay 117,provide means responsive to short-circuits oniy, comprising a currenttransformer 142 and a relay 143 that is energized thereby only upon theoccurrence of a short circuit on the generator. The relay 143, when soenergized, short-circuits the operating coil of the relay 119 (circuitZZ) and the resistor controlling relay 117 is deenergized in the samemanner as set.

forth above in connection with the slip relay 126 that is associatedwith the field winding of the motor.

The relay 143, being but an impulse relay, is disposed, when actuated,to energize a relay 144 which maintains its own holding circuit throughthe interlock switch 123 of the relay 119, as shown incircuit ZZ,untilthe relay 119 is deenergizecl and returns to its initial position.

The back interlock switch 1460f the resistor-shunting relay switch 117short-circuits the operating coil of the relay 144 to insure itsdeenergization to permit the relay 119 to be reenergized.

By means of the regulator-controlled rheostat 76 and the field limitingresistor 115, I am able to procure relatively sensitivecontrol andregulation of the generator voltage under all conditions. Whileconditions are such as merely to overload the generator within thecapacity of the motor, the current regulator controls the voltage of thegenerator to permit it to supply the predetermined maximum current.Under such conditions, the voltage of the generator is decreased by therheostatic regulator inserting resistance in the circuit of the shuntfield winding.

Upon the occurrence of a short-circuit, the field resistance is insertedto quickly reduce the excitation of the generator and, simultaneously,the rheostatic regulator operates also toinsert its resistance in thecircuit of the generator field. winding. Immediately upon the insertionof the limiting resistance in the circuit of the field winding, theshort-circuiting relay switch is deenergized to permit thereenergization of the relay 119 "to efiect the reenergization andreclosure of the resistor short-circuiting switch 117. The switch 117 isof the contactor type which operates under the control of the relay 119somewhat in the samemanner as the Tirrill regulator. in the circuit ofthe generator the rheostatic regulator is given suflicient time toinsert its resistance and assist in regulating the voltage of thegenerator, as may be necessary. The limiting resistor itself serves towipe off the peaks of the By 'insertinv the resistor field winding,

protect the apparatus against such abnormal I conditions as mightpreclude the transfer from starting to running conditions within apredetermined interval of time, and is also employed to disconnect themotor-generator unit from the system when the load decreases below apredetermined amount for a predetermined interval of time. The switch148 closes about one and one-half minutes after the relay 147 isenergized and the switch 149 closes about twenty to thirty minutes afterthe relay is energized, depending upon adjustments.

The energization of the time rela 147 is controlled by the two relays150 an 151, as illustrated in circuits A and AA. Normally, while theload exceeds the setting of underload relay 151, the relay 150 isdeenergized and its switch is maintained open. When the load decreasesto a predetermined value, the load relay 151 opens its switch to permitthe coil of relay 150 to beenergized. The switch of the relay 150thereupon connects the operating coil of the time relay 147 between thecontrol conductors 15 and 16 through the switch 31 of relay 30, asillustrated in circuit A.

The switch 148 of time relay 147 closes after one and one-half minutesbut since the interlock switch 44 of the starting switch 10, that is inseries therewith, is open, the lockout relay 24 will not be operated(circuit D).

After an interval of the order of twenty minutes, the switch 149 of timerela 147 closes. As illustrated in the left-han por' tion of circuit C,the operating coil of the master relay 21 will be short-circuited andthe relay 21 deenergized. The relay devices will thereupon be controlledto effect the dis connection of the motor generator from thedirect-current circuit and the alternatingcurrent circuit in thatsequence. Itis essential that the generator be disconnected from thedirect-current circuit bcfore the motor is disconnected from thealternatingcurrent circuit in order that the generator may not operateas a motor and tend to accelerate the speed.

The relay 21, upon being deenergized. opens its front interlock switchwhich deencrgizes the relay switch 27, as may be seen upon reference tothe circuit E. The relay switch 27, upon being deenergized, opens itsfront interlock switch 29 to disconnect the turn deenergizes the holdingcoils of the main direet-current switches 34 and 103 (circuit X),thereby efiecting the disconnection of the generator from thedirect-current circuit. The relay 108 is thereupon deenergized by theopening of the front interlock switch 106 of the direct-current switch34 (circuit W), and the switch 108 is subse quently opened todisconnectthe auxiliary control bus 15-A from the main control bus 15.The holding magnet 03 is consequently deenergized (circuit R) and therunning switch 11 is permitted to open to disconnect the motor 2 fromthe alternating-current circuit 1. The motor generator is thusdisconnected from both circuits in proper sequence, first from thedirect-current circuit and then from the alternating-current circuit.

In order to render the motor-generator unit immediately available forreconnection to the system after being disconnected there from, it isnecessary that thefield windings of the generator and of the'motor beimmediately deenergized. Upon reference to circuit F, it will be seenthat relay 30 is deenergized upon the opening of the relay switch 108joining'the control conductors 15 and 15A. Theswitch 32 of relay 30thereupon opens and permits the resistor 170 to be effective in limitinthe current traversing the shunt field winding of the exciter. Theexciter voltage immediately decreases and the excitation of'the motorand the generator fields is correspondingly diminished.

During the starting operation, if the'motor should be unable to start byreason of bearing trouble or other abnormal conditions, the switch 148of the timing relay 147 would close and, with interlock switch 44 of thestarting switch 10, would energize the operating'coil of the look-outrelay 24 to effect its operation, as illustrated by the second part ofcircuit D. The unit would remain locked out until the abnormalconditions were cleared and the look-out relay 24 normally reset by anattendant.

A phase-balance current relay 155 is provided to disconnect the unitfrom the system if the windings of the motor should become so afi'ectedas to cause a considerable unbalance between the currents traversing theseveral windings during operation. Under such conditions, the relay 155would close its switch which cooperates with the inter-lock switch 68 ofthe running switch 11 to shortcircuit the master relay 21v (circuit C)If such conditions obtain in the motor during starting of the motor, therela switch 155 will cooperate with the interloc switch 64: of therunning switch 11 and switch 28 of relay 27 to operate the lockout relay24 to preclude further operation of the unit until the abnormalcondition is cleared and the lock-out relay 2e reset, as is illustratedin circuit D.

Upon the occurrence of phase reversal in the alternating-currentcircuit, a phase relay 156 permits its switch to close to shortcircuitthe operating coil of the master relay 21 to preclude connection of themotor to v the system while such phase reversed condition exists.

Other relay devices may be arranged to short-circuit the operating coilof the master relay upon the occurrence of such conditions as ,aretransient in nature, as distinguished from those which are persistentand must be cleared by an attendant. For example, relay devicesresponsive to'thermal conditions in the motor or the generator may bearranged to close switches 157 and 158, or a reverse-current relay toclose a switch 159 to deenerg'ize the master relay and disconnect themotor-generator unit from the system.

l/Vhen abnormal conditions of a persistent nature occur, such as heatedbearings, or open circuits in the control equipment whereby transterfrom starting to running operation is precluded, protective devices maybe arranged to close switches 160 and 161 to operate the lock-out relay24:. As illustrated in circuit C, the circuit of the master relay. 2'].is then maintained open until an attendant may visit the station toclear the trouble and reset the relay 24:.

Each of several circuits, by means of any one of which the lockout relay2% may ,be

energized, is connected to the main operat ing coil of the relay 2athrough a separate auxiliary coil 24a of the same relay. Each ot thecoils 24m is provided with an armature member 2% to which a movableannunciator member 240 is connected. Thus, when any circuit is closed toenergize the main operatin coil of the relay 2%, the auxiliary coil 8 o0 n n 240: that is connected in series wlth that circuit is alsoenergized.

When one of'he auxiliary coils 24a is enengined, armature member 245 isactuated to 'move its annuciator member 240 to the right. Anyannunciator member that is so actuated remains in such position untilthe relay 24 is reset manually, at which time the'attendant is informedasto which cir: cuit caused the energization of the lockout relayaccording to which annuciator member has been actuated. He thereforeknows what kind. of a fault caused the station to be locked out ofservice and the locating of the trouble is thereby greatly facilitated.

Recapitulating, my invention comprehends, among other generalarrangements and combinations disclosed herein, the following broadprinciples:

1. An arrangement whereby abnormal conditions of transient and ofpersisting character may be distinguished and utilized to control anautomatic station in different manners;

2. An arrangement whereby an attendant may be informed which of aplurality of protective devices has effected the automatic shutting downand locking out of the stations by reason of the occurrence of abnor malconditions of a persisting character;

3. An arrangement whereby non-synchronous operation of a synchronousmachine may be detected to procure protection from overheating 4. Anarrangement whereby upon such non-synchronous operation of a synchronousmotor, a generator driven thereby may be so controlled as to permit themotor to reattain normal synchronous operation and 5. An arrangementwhereby a generator may be controlled normally to assume a predeterminedload, but permitted, while be ow a predetermined temperature, to assumea greater load.

My invention is not limited to the specific apparatus that isillustrated or to the particular arrangement thereof, since they may bevariously modified without departing from the spirit and scope of myinvention, as set forth in the appended claims.

I claim as my invention:

1. In a power distributing system, the combination with a synchronousmotor, a direct-current generator to be driven thereby and an exciterenerator provided'with a shunt field win ing for energizing the fieldmagnet windings of both the motor and the generator, of a resistor inthe circuit of the field winding of the exciter and means dependent upona condition of the motor and the generator for controlling theeffectiveness of the resistor. 1

2. In a power distributing system, the combination with a synchronousmotor, a direct-current generator to be driven thereby and an externalsource of electromotive force for energizing the field windings of boththe motor and the generator, of means for controlling the effectivenessof said elec-.

tromotive force upon the motor and generator windings, and meansresponsive to an abnormal condition of the motoror the generator forcontrolling said means.

3. In a distribution system, the combination with a motor and agenerator respectively provided with a field winding, of a resistor incircuit with the field winding of the generator and means responsive toan abnormal condition of the field winding of the motor for controllingthe effectiveness of the resistor.

4. In a distribution system, the combination with a synchronous motorand a generator respectively provided with a field winding, of aresistor in. circuit with the field winding of the generator and meansresponsive to a predetermined slip of the motor for control ing theeffectiveness of the resistor.

5. In a distribution system, the combination with a synchronous motorand a enerator respectively provided with a eld winding, of a resistorin circuit with the field Winding of the generator and means energizedonly when the motor is operating at a speed other than synchronous speedfor controlling the effectiveness of the resistor. a

6. In a distribution system, the combination with a motor and ageneratorre'spectively provided with a field winding, of a resistor incircuit with the field winding of the generator and means energized byan electromotive force induced in the field winding of the motor bytransformer action for controlling the effectiveness of the re sistor.

7. The combination with a synchronous motor, a direct-current generatorand means for connecting them between a supply and a load circuit, ofmeans for controlling the voltage of the generator comprising a resistorinthe circuit of the field winding of the generator, and means operativewhen the motor pulls out of step for rendering the resistor effective toreduce the generator voltage. i

8. The combination with a generator provided with a shunt field winding,and a synchronous motor for driving the generator, of a resistor in thecircuit of the generator shunt field winding, short-circuiting means forthe resistor, and means for controlling the short-circuit-ing meanscomprising means responsive to non-synchronous operation of the motorand means responsive to the current traversing the generator.

k 9. The combination with a generator provided with a shunt fieldwinding, and-a synchronous motor for driving the generator, of aresistor in the circuit of the generator shunt field winding,short-circuiting means for the resistor, means responsive tonon-synchronous operation of the motor for controlling theshort-circuiting means to render the resistor efiective, and meansoperative upon adecrease 'in the current traversing the generator to apredetermined value for controlling the short-circuiting v means torender the resistor ineffective.

v-erator.

11. The combination with a synchronous motor-generator set, of meansresponsive to a predetermined abnormal armature reaction upon the fieldWinding of the motor for controlling the effective resistance of thefield winding of the generator.

12. The combination with a load circuit and a generator for sup lyinenergy thereto, of means for control ing the generator to limitthetranslation of current to the circuit to a predetermined maximum value,and means responsive to the thermal condition of a generator winding forcontrolling said current-controlling means.

13. The combination with a load circuit and a generator for supplyingenergy thereto, of means for controlling the generator to'limit thetranslation of current to the circuit to apredetermined maximum value,and means operative, when the temperature of a predeterminedportion oithe generator is less than a predetermined value, to modify theoperation oithe current-controlling means.

14. The combination with a load tircuit and a generator for supplyingenergy thereto, of means for controlling the generator to limit thetranslation oi current to the circuit to a predetermined maximum value,and means connected to a winding of the generator to control theoperation of the current-controlling means.

15. The combination with a load circuit and a generator for supplyingenergy there to, of means for controlling the generator to limit thetranslation of current to the circuit to a predetermined maximum value,comprising an operating. winding and means for modifying the torque ofsaid operating winding under predetermined temperature conditions in thegenerator.

- 16. The combination with a load circuit I and a generator for supplyinenergy thereto, of means for controlling t generator to limit thetranslation of current to the circuit to a predetermined maximum value,coinprising an operative winding and a second winding differentiallyefiective relative thereto for controlling the effect thereof supplyingcurrent to aload circuit, at a regulator for controlling the voltage ofthe generator to limit the translation of current thereby to aredeterminel value during normal operation and means for controlling theregulator to limit the translation of current to a greater value beforethe temperature of the generator attains a predetermined value.

18. The combination witha generator'forsupplying current to a loadcircuit, of a regulator for normally limiting the assumption of load bythe generator to a predetermined value and for limiting such assumptionto adifl'erent predetermined value under predetermined temperatureconditions in the generator.

19. The combination with a generator for supplying current to a loadcircuit, of a regulator comprising means energized from the generatorfor controlling the generator to limit the assumption of load thereby toa predetermined value while the temperature thereof is less than apredetermined value, and to limit the assumption of load to a lowerpredetermined value when the cordance with the current traversing, and rthe temperature of, a winding.

'21. The combination with an electriccircuit and a translatingapparatus, of means for controlling the translation of energytherehetween comprising two diiierentially operative windings, and meansfor controlling the energization thereof respectively in accordance withthe value of current traversing the windings of the apparatus and inaccordance with the temperature of a predetermined portion of theapparatus.

22. The combination with a synchronous machine provided with a fieldwinding, of means for detecting nonsynchronous operation of the machinecomprising a current transformer in circuit with the field winding andan electro-responsive device connected to the secondary, winding of thetransformer, and means con-trolledhy the electro-responsive device .forcausing the machine to resume synchronous operation.

23. The combination with a synchronous motor and a generator providedwith a shunt field winding, of means responsive to non-synchronousoperation of the motor for controllin *the excitation of the generatorfield Win ing to reduce the load upon the generator until the motor canagain-accelerate to synchronous speed, and for then controlling theexcitation of the generator to cause it to reassurpe the load.

24. The combination with a synchronous motor and a generator providedwith a shunt field. winding, of a relatively slowly regulatable resistorin circuit with the generator field winding, a relatively quicklyregulatable resistor in said circuit, means for normally regulating thefirst-mentioned resistor to maintain normal current conditions and meansresponsive to abnormal conditions in either the motor or the generatorfor controlling both resistors.

25. The combination with a synchronous motor and a generator providedwith a shunt field winding, of a variable resistor and a fixed resistorin circuit with the generator field winding, means normally operativefor. controlling the variable resistor comprising a current regulatorenergized in accordance with the load on the generator, and meansoperative under abnormal conditions for controlling the effectiveness ofboth resistors comprisingmeans responsive to non-synchronous operationof the motor. 26. The combination with a synchronous motor and agenerator, each being provided with a shunt field winding, of a variableresistor and a fixed resistor in circuit with the generator fieldwinding, means normally operative for controlling the variable resistorcomprising a current regulator energized in accordance with the load onthe generator,-

and means operative under abnormal conditions for controlling theefi'ectiveness of both resistors comprising means responsive to abnormalenergization of the motor field winding, and means for rendering saidcontrolling means ineffective until the motor and the generator havebeen connected to their respective circuits.

27. The combination with anfalternatingcurrent circuit, a direct-currentcircuit and a rotary transformer to be connected therebetween, ofswitching means for connecting the transformer to the respectivecircuits means for controlling the ener ization of the switching meansand means or controlling said controlling means upon the occurrence ofabnormal conditions, to effect the disconnection of the transformerfirst from the direct-current circuit and then from thealternating-current circuit.

28. In an automatic station, the combination with an alternating-currentcircuit, a direct-current circuit and a rotary transformer to beconnected therebetween, of switching devices to connect the transformerbetween the respective circuits, a source of control energy, a relayswitch for connecting the alternating-current switch 'to the source ofener a second relay switch in parallel therewith also connecting thealternating-current switch to the source of energy, means controlled bythe direct-current switch for controlling said second relay switch andmeans responsive to a predetermined abnormal condition in the statio forrendering the first-mentioned relay switch inefiective.

29. In an automatic station, the combinetion with an alternating-currentcircuit, a direct-current circuit and a rotary transformer 'to beconnected therebetween, of a. switch between the alternating-currentcircuit and the transformer, a second switch between the transformer andthe direct-current circuit, a source of control energy, means forconnecting the first-mentioned switch thereto, a secondsource of energy,means for connecting'the second-mentioned switch thereto, means forcontrolling both connecting means, means for rendering said controllingmeans for the connecting means inefi'ectire upon the occurrence of apredetermined condition in the station and means for delaying thedisconnection by the first-mentioned switch until the second-mentionedswitch has operated to disconnect the transformer from thedirect-current circuit.

30. In an automatic station, the combination with an alternating-currentcircuit, a direct-current circuit and a rotary transformer to beconnected therebetween, a switch between the alternating-current circuitand the transformer, a second switch between the transformer and thedirect-current circuit, a source of control energy,

means for connecting the first-mentioned switch thereto, supplementalmeans controlled bythe second-mentioned switch for connecting thefirst-mentioned switch to the source of control energy, and means resnsive to a predetermined condltion for e ecting the disconnection of thetransformer from the two circuits by rendering the connecting meansassociated with the first-mentioned switch ineffective and by renderingthe second-mentioned switch operative to control the supplementalswitch.

31. In a power system, the combination with a generator provided with ashunt field winding and a rheostat in circult therewith,

of a fixed resistor also in circuit therewith, a regulator forcontrolling the rheostat in accordance with one predetermined electricalcondition in the generator and means for controlling the rheostat andthe resistor upon the occurrence of another predetermined condition inthe generator.

32. In a power system, the combination with a generator provided with ashunt field winding and a rheostat in circuit therewith, of a fixedresistor also in circuit therewith, a regulator for controlling therheostat in accordance with the load on the generator under apredetermined value, and means responsive to short-circuit conditionsfor controlling both the resistor and the rheostat.

33. In a power system, the combination with agenerator provided with ashunt field winding and a rheostat in circuit therewith,

of a fixed resistor also in circuit therewith, a regulator forcontrolling the rheostat in accordance with the load on the generatorunder a predetermined value, and means re sponsive to short-circuitconditions for rendering the resistor and the rheostat entirelyeli'ectlve in the circuit of the winding.

34. The combination with a synchronous dynamo-electric machine providedwith a field-magnet winding, and a load for the machine, of meanscomprising a current transformer in circuit with the field-magnetwinding for controlling the load on the machine. V

35. The combination with a synchronous dynamo-electric machine providedwith a field-magnet winding, and a load for the machine, of meanscomprising a current tranformer in circuit with the field-magnet windingfor controlling the load on the machine when the machine ceases tooperate synchronously.

37. The combination with a synchronous dynamo-electric machine providedwith a field-magnet winding, and a load for the transformer in circuitwith the field-magnet Y Winding and means controlled by the currenttransformer for reducing the load on the machine when it is operatingnon-synchronously.

39. The combination with a synchronous dynamoclcctric machine providedwith a field-magnet winding, and a load for the machine, of meanscomprising a current transformer in circuit with the field-magnetwinding and means controlled by the current transformer for reducing theload on the machine when it is operating non-synchrochronousiy to causeit to operate synchronousiy,

In testimony whereof, I have hereunto subscribed my name'this 21st dayof May 1923. j

CHARLES A. BUTCHER.

